This is a guide showing all of the unlocks for Retro/Grade in Challenge Mode, just in case you don't feel like playing through all the challenges to unlock some specific stuff. Like Octodad. Everybody loves Octodad....

Retro/Grade - Achievements

by @The1AndMany

This guide shows how to get each achievement in Retro/Grade.
Be warned: Most of these are incredibly hard, but every one of them is still possible!...